Chemistry - July 2007

In an electrolysis experiment, a student observed that his unknown metal anode lost 0.208g while a total volume of 96.30 mL of H2 was being produced. The temperature in teh laboratory was 25 degrees Celcius and the barometric pressure was 748 mm Hg. At 25 degrees Celcius the vapor pressure of water is 23.8 mm Hg. To find the mass of his metal, he filled in the blanks below. Fill in the blanks as he did.

PH2=Pbar-VPh2o =_______mm Hg=______atm
VH2=____mL=_______L
T=______K
nH2=_____moles nH2=PV/RT (where P=PH2)

1 mole H2 requires passage of ____________faradays

No. of faradays passed = ___________

Loss of mass of metal anode =_______g

No. grams of metal lost per faraday passed = no. grams lost/no. faradays passed=__________g=EM

The student was told that his metal anode was made of iron.

MM Fe=__________g. The charge n on the Fe ion is therefore__________.

Can anyone help? I'm confused....

2007-07-30 13:34:58 · 2 answers · asked by Anonymous

Okay there are 2 questions. can someone help me solve these problems and explain them.

Ethylene glycol, C2H6O2, is a liquid that is the base of the antifreeze you use in your car's radiator. it has a density of 1.1335g/cm^3 at 20 degrees Celsius. If you need 500 mL. of this liguid,what mass of the compound, in grams, is required?

A sample if unknown metal is placed in a graduated cylinder containing water. The mass of the sample is 37.5g, and the water levels before and after adding the sample to the cylinder in the figure. Which metal in the following list in likely the sample(d is the density of the metal)?

A)Mg. d=1.75g/cm3
B)Fe, d+ 7.87 /cm3
C)Ag, d=10.5g/cm3
D)Al, d=2.70 g/cm3
E)Cu, d= 8.96 g/cm3
F) Pb, d= 11.3 g/cm3

Left figure the one without the metal is 7
Right Figure with the metal is 21

2007-07-30 12:13:44 · 2 answers · asked by Gamer G 4

Thanks.

2007-07-30 11:08:32 · 3 answers · asked by Anonymous

what is the difference between a ground state electron configuration and a excited state one?

2007-07-30 10:56:43 · 0 answers · asked by Anonymous

Each of the following elements is able to form an ion. Using the periodic table, predict the charge of the ion.

(a) Mg

(b) Al

(c) K

(d) S

can anyone explain how im supposed to do this. im new to chem and i was wondering if the charge of an ion is the same as its first oxidation state or.. what???

2007-07-30 10:50:24 · 4 answers · asked by Anonymous

2007-07-30 10:47:30 · 5 answers · asked by Miss D 7

Can steam be heated to the point in which the steel or iron container would reach it's melting point? I understand that the heat of the steam will increase with pressure, does it turn into plasma at some point?

2007-07-30 10:37:22 · 4 answers · asked by Charles B 1

Determine the heat of reaction for the decomposition of one mole of benzene to acetylene C6H6(l)-->3C2H2(g) given the following thermochemical equations:

2C6H6(l)+15O2(g)-->12CO2(g) + 6H2O(g) Delta H = -6271kj
2C2H2(g)+ 5O2(g)-->4CO2(g) 2H2O(g) Delta H = -2511kj

2007-07-30 10:33:16 · 3 answers · asked by Anonymous

2H2O(g) -----> 2H2(g)+O2(g)

2007-07-30 10:13:41 · 2 answers · asked by Silvina M 1

1 mole of COCl2(g) was placed in a 500ml reaction flask. At equ'm the concentration of the product Cl2(g) was 0.7M. The other product is CO(g). Calculate K.

Please show your work! Thanks :D

2007-07-30 09:41:00 · 2 answers · asked by Mickey mouse 1

Actually i cant undestand that how to do antilog operation on calculator or is tehre anyother way?
For example: [H3O+]= 10 (-7.3)pH
[H3O+]=5.01x10`-8 (-8 is the power) how they get that answer, i found this from books example.

2007-07-30 09:30:25 · 4 answers · asked by chem-mystry 2

2007-07-30 09:09:03 · 8 answers · asked by Anonymous

The Empirical formula of two compounds are CH4. If molar mass of one is 32g/mole and the others is 48g/mole; then find out the chemical formulas of these compounds?
Its the tricky one, isnt it?

2007-07-30 08:13:44 · 6 answers · asked by chem-mystry 2

2007-07-30 07:40:53 · 4 answers · asked by Anonymous

reagents used in the conversions
a- ethanol to but-1-yne
b- 1-bromopropane to 2-bromopropane
c- toluene to benzyl alcohol
d- benzyl alcohol to 2-phenylethanoic acid
e- ethanol to propanenitrile
f- aniline to chlorobenzene
g- 2-chlorobutane to 3,4-dimethylhexane
h- 2- methyl-1-propane to 2-chloro-2-methylpropane
i- ethyl chloride to propanoic acid
j- but-1-ene to n-butyliodide
k- 2-chloropropane to 1-propanol
l- isopropyl alcohol to iodoform
m- chlorobenzene to para-nitrophenol
n- 2-bromopropane to 1-bromopropane
o- chloroethane to butane
p- benzene to diphenyl
q-aniline to phenylisocyanide

it would be very helpful if u could solve just one.

2007-07-30 06:55:31 · 2 answers · asked by Anonymous

Is plutonium man-made or organic? How do they get it?

2007-07-30 05:35:36 · 2 answers · asked by Anonymous

I need more answers regarding the indication of a chemical change in a substance...an absolute example is "..the formation of bubbles"....or "...release of hydrogen".

What more can you guys give?

2007-07-30 04:15:51 · 7 answers · asked by Jed Stephen 3

A. 39/400

B. 390/400

C. 39/40

D. 39/4000

2007-07-30 03:30:24 · 8 answers · asked by exzizting@sbcglobal.net 1

2007-07-30 03:13:50 · 5 answers · asked by cuongnguyen4326 1

A beaker with 190mL of an acetic acid buffer with a pH of 5.00 is sitting on a benchtop. The total molarity of acid and conjugate base in this buffer is 0.1M . A student adds 8.70mL of a 0.420M HCl solution to the beaker. How much will the pH change? The pKa of acetic acid is 4.76.

Express your answer numerically. Use a minus (-) sign if the pH has decreased.

2007-07-30 03:08:44 · 1 answers · asked by Anonymous

air,water,acid and salt solution....

the ans is air,water and acid...
do u all agree with the ans???

i think is acid and salt solution only

2007-07-30 01:44:40 · 6 answers · asked by red devil 4

I found that alloys is a type of homogenous mixture. What exactly is homogenous mixture? (I've checked wiki and found that the explanation is complicated, please explain in simpler form, thanks!)

2007-07-30 01:13:49 · 8 answers · asked by Lai Yu Zeng 4

i need it for a robot, should i use a polarimeter, a spectroscope, a refractometer? pls tell me

2007-07-29 23:09:27 · 3 answers · asked by erzebet 2

I need a Chemical element that related to the number 6 and related to cooking (like NaCl,but i can't find the connection to the number 6)
p.s
I know this sounds funny ,but this element may also relate to bicycle

2007-07-29 22:14:04 · 3 answers · asked by Anonymous

2007-07-29 20:14:23 · 5 answers · asked by parama b 1

example: ph=3.77, pka= 3.85, acid [.10]. what will the concentration be for the base?

P.S. I can solve it without this henderson equation but I want to know how to manipulate this equation.

2007-07-29 18:18:48 · 2 answers · asked by Anonymous

If I take a small piece of dry ice, and put it in 5 table spoons of water in a glass what would happen?

2007-07-29 18:13:15 · 9 answers · asked by Anonymous

I think its used for lawns and on instant cold packs. What else can you use it for?

2007-07-29 18:11:43 · 4 answers · asked by Anonymous

The reaction occurs in this form:
Zn(s) + Cu(NO3)2(aq) --> Zn(NO3)2(aq) + Cu(s)

-What is the net ionic equation?
-Calculate the # of moles of Cu(NO3)2 present.
-What is the mass of Cu(s) produced by this setup?
-If this reaction is repeated, this time with a large quantity of Cu(NO3)2 solution, how much Cu(s) will be produced?

Thanks! I was stumped by this question...

2007-07-29 17:38:51 · 2 answers · asked by Anonymous

2007-07-29 17:29:13 · 2 answers · asked by john ruffy t 1